/Engine/Plugins/Animation/LiveLink/Source/LiveLinkMovieScene/Public/MovieScene/MovieSceneLiveLinkBufferData.h
This function is the one that's called when recording live link incrementally. We move the values over from our saved Location, Rotation and Scale buffers into the specified float channels and then reset our buffers, re-using it's memory for the next iteration. We also fix any euler flips during this process, avoiding iterating over the data once again during Finalize.
void AppendToFloatChannelsAndReset ( int32 StartIndex, [TArray](API\Runtime\Core\Containers\TArray)< [FMovieSceneFloatChannel](API\Runtime\MovieScene\Channels\FMovieSceneFloatChannel) > & FloatChannels )